Fourteen-year-old Iruma Suzuki has been unfortunate all his life, having to work to earn money for his irresponsible parents despite being underage. One day, he finds out that his parents sold him to the demon Sullivan. However, Iruma's worries about what will become of him are soon relieved, for Sullivan merely wants a grandchild, pampering him and making him attend the demon school Babyls. At first, Iruma tries to keep a low profile in fear of his peers discovering that he is human. Unfortunately, this ends up being more difficult than he expected. It turns out that Sullivan himself is the chairman of the school, and everyone expects him to become the next Demon King! Iruma immediately finds himself in an outrageous situation when he has to chant a forbidden spell in front of the entire school. With this, Iruma instantly earns a reputation he does not want. Even so, he is bound to be roped into more bizarre circumstances.

After many trials and tribulations, Iruma Suzuki is finally happily living among demons despite having to hide his true identity as a human. Even more so, he has now found his ambition in life: keep ranking up in this world! However, that plan is halted when Iruma's club is temporarily dismissed, and he is forced to be part of the student council, known for its strictness toward rowdy students. Its cold-hearted president is Amelie Azazel, Iruma's friend. Although Iruma is not used to following their rigid schedule and many rules, he still wants to prove himself and help Amelie alongside all of the other members of the council. But trouble arises when Amelie's personality completely changes due to strange circumstances, putting the student council's reputation in jeopardy. Will Iruma be able to save them and avoid having the whole school turn into pure chaos?

Following their heroic efforts at Walter Park, the students of the Misfit Class return to Babyls Demon School after their summer vacation. What awaits them is not only adoration and admiration but also the shocking revelation that, in order to stay in the luxurious Royal One classroom, the entire class must be promoted to Dalet rank before entering the second year. As the Harvest and Music Festivals are right around the corner, there seem to be ample opportunities to rank up. Doing so will not be simple, however, as no class thus far has managed to accomplish such a feat. Hoping to give the misfit class a chance to achieve the improbable, the school appoints special tutors to aid in confronting the challenges that lie ahead. With his sights set beyond Dalet, Iruma Suzuki decides to take strides toward the goal of ranking up, starting with gaining acknowledgment from his special tutor: the short-tempered and selfish Bachiko Barbatos.